The present invention relates to a book binding method and a book binding system for manufacturing a saddle-stitched booklet.
FIG. 8 is a front view schematically illustrating a constitution of a conventional saddle stitching bookbinding system. In FIG. 8, the numeral 51 designates a collating machine having a plurality of sheet feeders 51a aligned in a vertical direction. The sheet feeders 51a supply sheets P1-Pn which make different pages, one by one, respectively. The numeral 52 designates a saddle stitching machine and the numeral 53 designates a press roller. The numeral 54 designates a table for receiving saddle-stitched bound booklets and the numeral 55 designates a saddle-stitched bound booklet. The numeral 51b designates a conveyor belt 51b conveying a set of sheets P comprised of gathering of the sheets. The saddle stitching machine is provided with a conveying belt 52a conveying the set of sheets P to a stitching station, a stitching head 52c arranged for vertical movement at the stitching station so as to drive a stitching wire into the center portion of the set of sheets P, a stopper 52b for positioning the set of sheets P conveyed on the conveying belt 52a in place, conveying belts 52d conveying the stitched set of sheets to a folding station, a folding knife 52e arranged for reciprocating motion so as to fold the stitched set of sheets along its center line, a stopper 52d for positioning the set of sheets conveyed on the conveying belts 52d and a pair of nip rollers 52g providing the stitched set of sheets pushed forwardly by the folding knife 52e with the definite fold line.
However, according to the conventional book binding system, a set of sheets and thereafter folding the stitched set of sheets along the center line thereof, as the number of sheets forming a booklet increases, the fold line of the bounded booklet is rounded and bulged, which causes a problem of degradation in appearance and feature of the booklet.
Furthermore, in the above-mentioned conventional book binding system, the motion of the collating machine is synchronized with the motion of the post-processing machine such as the sheet stitching unit, the sheet folding unit and so on by activating the collating machine at slower speed than a processing speed of the post-processing machine and starting the post-processing machine upon detection of reception of the stack of sheets, which causes a problem that both the working speed of the collating machine and the processing speed of the post processing machine are restricted so that the whole speed of the book binding processing cannot be increased.